Mars: magnetic tail twisted by the solar wind

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NASA’s Mars Atmosphere and Volatile Evolution Mission (MAVEN) is in the orbit of Mars collecting data on how this planet has lost much of its atmosphere as well as water, transforming itself from a place that could have sustained life for thousands of millions of years, to a cold and inhospitable place, which we know today.

Mars has an invisible magnetic “tail”, which is twisted by interaction with the solar wind, according to new research using the data collected by the MAVEN probe.

Now, according to the team, the process that forms this twisted tail may also allow some of the already thin atmosphere of Mars to escape into space.

“We have discovered that the magnetic tail of Mars, or magnetic magneto, is unique in the Solar System. It is not like the magnetocauda of Venus, a planet without its own magnetic field, nor is it like that of Earth, a planet surrounded by its own internally generated magnetic field. Instead, it’s a mix of the two”.

Said Gina DiBraccio of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The MAVEN project scientist presented her research at a press conference on October 19 during the 49th annual meeting of the Division of Planetary Sciences of the American Astronomical Union in Provo, Utah.

The team found that a process of name “magnetic reconnection” should play a key role in creating the Martian magnetocauda because, in the event of this reconnection, this would cause a torsion in the tail.

“Our model predicted that magnetic reconnection will cause the Martian magneto-wedge to rotate 45 degrees to what is expected based on the direction of the magnetic field carried by the solar wind. When we compared these predictions with the MAVEN data from the directions of the Martian magnetic fields and the solar wind, they were in very good agreement”, DiBraccio said.

Thus, Mars has lost its global magnetic field for billions of years and now has only remaining magnetic fields and “fossils”, already embedded in some regions of its surface. According to the new study, magnetocauda of Mars is formed when the magnetic fields carried by the solar wind join with the magnetic fields embedded in the Martian surface in a process called magnetic reconnection.

The solar wind is an electrically conductive gas stream continuously “blown” from the Sun’s surface into space at about 1.6 million kilometers per hour. It carries with it magnetic fields of the Sun, if the field of the solar wind is oriented in the opposite direction of the field of the Martian surface, the two fields join in magnetic reconnection.

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